Multimedia streams which use control information to associate audiovisual streams

ABSTRACT

A system and method for wirelessly transmitting audiovisual information. A first plurality of packets including audiovisual information may be generated. A second plurality of packets including error correction coding information for the audiovisual information may be generated. Control information for associating the error correction coding information with the audiovisual information may be generated, and a third plurality of packets including the control information may also be generated. The plurality of packets, including the first, second, and third pluralities of packets, may be transmitted to a mobile device in a wireless manner. The control information may inform the mobile device of the association of the first error correction coding information with the audiovisual information.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.15/346,213 titled “Multimedia Streams Which Use Control Information toAssociate Audiovisual Streams” filed Nov. 8, 2016; which is acontinuation of U.S. patent application Ser. No. 13/629,844 titled“Wireless Transmission of Multimedia Streams Which Uses ControlInformation to Associate Error Correction Coding With an AudiovisualStream” filed Sep. 28, 2012, now U.S. Pat. No. 9,515,776 issued on Dec.6, 2016; which is a continuation of U.S. application Ser. No. 12/472,892titled “Transmission of Multimedia Streams to Mobile Devices With CrossStream Association” filed on May 27, 2009, now U.S. Pat. No. 8,332,896issued on Dec. 11, 2012; which is a continuation-in-part of U.S.application Ser. No. 12/167,708 titled “Mobile Television BroadcastSystem” filed on Jul. 3, 2008, now U.S. Pat. No. 8,151,305 issued onApr. 3, 2012; which claims benefit of priority to provisionalapplications Ser. No. 60/948,185 titled “Robust Mobile TV BroadcastSystem” filed Jul. 5, 2007, Ser. No. 60/958,585 titled “Robust Mobile TVBroadcast System” filed Jul. 5, 2007, and Ser. No. 60/999,039 titled“Robust Mobile TV Broadcast System” filed Oct. 14, 2007, all of whichare hereby incorporated by reference in their entirety as though fullyand completely set forth herein.

U.S. application Ser. No. 12/472,892 also claims benefit of priority toprovisional application Ser. No. 61/130,344 titled “Enhanced Mobile TVSystem” filed on May 31, 2008, which is hereby incorporated by referencein its entirety as though fully and completely set forth herein.

FIELD OF THE INVENTION

The present invention relates to a mobile television broadcast system,and more specifically in one embodiment relates to enhancement of thecurrent ATSC Digital TV broadcast system for mobile services to mobileand handheld devices.

DESCRIPTION OF THE RELATED ART

The ATSC (Advanced Television Systems Committee) standard relates to adigital television format which will replace the analog NTSC televisionsystem. The ATSC standard is a high definition television standard thatproduces standard 4:3 or wide screen 16:9 images up to 1920×1080 pixelsin size—more than six times the display resolution of the earlier NTSCstandard. The ATSC standard makes provisions to transport multiplestandard-definition “virtual channels” broadcast on a single 6 MHz TVchannel. The ATSC standard also includes “theater quality” audio usingthe Dolby Digital AC-3 format to provide 5.1-channel surround sound. TheATSC standard also provides numerous auxiliary datacasting services.

The ATSC standard uses the MPEG-2 systems specification forencapsulation (transport) of data. More specifically, ATSC uses the188-byte MPEG transport stream packets to carry data. MPEG-2 is alsoreferred to as “transport stream”, “MPEG-TS”, or simply “TS”. At thereceiver side, before decoding of audio and video occurs, the receiverdemodulates and applies error correction to the signal. Then, thetransport stream may be demultiplexed into its constituent streams. Avideo codec, e.g. MPEG-2, H.264, VC-1, is used for encoding and decodingvideo, subject to certain constraints.

Previously, mobile reception of digital television stations transmittedusing the ATSC standard has been difficult to impossible. For example,mobile reception of digital television stations is very difficult whenmoving at vehicular speeds. Therefore, there is a need for an improvedsystem and method for transmission and/or reception of digitaltelevision signals for improved mobile reception.

SUMMARY OF THE INVENTION

Various embodiments are presented of a system and method for wirelesslycommunicating audiovisual information. One set of embodiments involves asystem and method for wirelessly transmitting audiovisual information toa mobile device. Another set of embodiments involves a system and methodfor wirelessly receiving audiovisual information by a mobile device. Theaudiovisual information may be packetized according to the ATSC(Advanced Television Standards Committee) standard, e.g., using 8-VSBmodulation.

The method for transmitting audiovisual information to a mobile devicemay include generating a first plurality of packets including firstaudiovisual information. The first plurality of packets may also includeerror correction coding information of a first type; or, there may bemultiple types of error correction coding information in the firstplurality of packets. A second plurality of packets including firsterror correction coding information for the first audiovisualinformation may also be generated. The first error correction codinginformation may be formed using a first error correction encodingmethod, while the error correction coding information in the firstplurality of packets may be formed using a second error correctionencoding method. The first and second error correction encoding methodsmay be the same or may be different error correction encoding methods.

The first error correction coding information may include a firstpattern of error correction coding information and a second pattern oferror correction coding information. The first and second patterns oferror correction coding information may be complementary to each other;alternatively, they may overlap or be identical. The first and secondpatterns of error correction coding information may be separated in timeand/or frequency; in other words, they may be configured fortransmission at different times and/or on different frequencies.

Control information, including commands for associating the first errorcorrection coding information with at least a portion of the firstaudiovisual information, may also be generated. Thus, although the firsterror correction coding information and the first audiovisualinformation may be in different streams (e.g., different sets ofpackets), and may in some embodiments be transmitted separately in timeand/or on different frequencies, the control information may be usableby a mobile device (e.g., may inform the mobile device) to associate thefirst error correction coding information and the first audiovisualinformation with each other, thereby enabling the mobile device to usethe first error correction coding information in processing the firstaudiovisual information. Once the control information is generated, thecontrol information may be included in the second plurality of packetswith the first error correction coding information, or may be includedin a third plurality of packets.

The plurality of packets, including the first, second, and (possibly)third pluralities of packets, may be wirelessly transmitted, e.g., to amobile device. The plurality of packets may be transmitted by atransmitter, e.g., including an antenna.

In some embodiments, there may be additional packets generated. Forexample, in one embodiment, a fourth plurality of packets, includingsecond audiovisual information, may be generated. The second audiovisualinformation may be completely complementary to the first audiovisualinformation, or partially overlapping (i.e., at least a portion of thefirst and second audiovisual information may be the same audiovisualinformation), or the first and second audiovisual may be identical orredundant. The fourth plurality of packets may also include errorcorrection coding information, similar to the first plurality ofpackets. In some embodiments, even if the first and second audiovisualinformation are partially or entirely redundant, the error correctioncoding information for each may be partially or entirely complementary.Alternatively, the first and fourth pluralities of packets may beidentical, including error correction coding information; for example,one set of packets may be backup information, sent at a different timeor on a different frequency than the other set of packets. It shouldfurther be noted that it is possible that the first and fourthpluralities of packets (the first and second audiovisual streams) may beconfigured for transmission at separate times and/or frequencies,regardless of whether they are identical or not. In some embodiments,neither (or, only one of) the first and fourth pluralities of packetsincludes error correction coding information; for example, any errorcorrection coding information for the first and second audiovisualinformation may be sent separately in another stream (e.g., in anotherset of packets). The commands in the control information may alsoassociate the first and second audiovisual information. This may alsoinclude associating any error correction coding information for thefirst and second audiovisual information, whether that error correctioncoding information is located in the same plurality of packets or in adifferent plurality of packets as the audiovisual information for whichit is intended.

A fifth plurality of packets may also be generated. The fifth pluralityof packets may include second error correction coding information, e.g.,for the second audiovisual information. The second error correctioncoding information may be a (partially or entirely) complementarypattern of error correction coding information to the first errorcorrection coding information. For example, the first and secondaudiovisual information may be associated, and if the respective errorcorrection coding information for the first and second audiovisualinformation is complementary, the complementary patterns of the firstand second error correction coding information would together form astronger form of error protection. Thus, the commands in the controlinformation may also associate the second error correction codinginformation with the second audiovisual information, and in someembodiments, may associate the first audiovisual information and thefirst error correction coding information with the second audiovisualinformation and the second error correction coding information.Alternatively, the commands in the control information may simplyassociate the first audiovisual information with the first errorcorrection information, the second audiovisual information with thesecond error correction information, and the first audiovisualinformation with the second audiovisual information, and a mobile devicereceiving said control information may implicitly associate the seconderror correction coding information with the first audiovisualinformation and the first error correction coding information with thesecond audiovisual information due to the explicit associations in thecontrol information.

The method for wirelessly transmitting audiovisual information to amobile device may be performed partially or entirely by a system, whichin various embodiments may include some or all of memory for storing theaudiovisual information, transmit logic coupled to the memory andconfigured to generate the packets and the control information, and atransmitter for transmitting the pluralities of packets.

The method for wirelessly receiving audiovisual information by a mobiledevice may include wirelessly receiving a plurality of packets. Thepackets may include first and second pluralities of packets (and in someembodiments, third, fourth and fifth pluralities of packets), which maycorrespond to the first and second pluralities of packets (and in someembodiments, the third, fourth and fifth pluralities of packets) asdescribed above with respect to the method for wirelessly transmittingaudiovisual information to a mobile device, according to any of thevarious embodiments described above.

The first error correction coding information (in the second pluralityof packets) may be associated with at least a portion of the firstaudiovisual information (in the first plurality of packets) based on thecontrol information. If there are fourth and fifth pluralities ofpackets, the second error correction coding information may also beassociated with the second audiovisual information based on the controlinformation. Likewise, one or more of: the first audiovisual informationand the second audiovisual information; the first audiovisualinformation and the second error correction coding information; or thesecond audiovisual information and the first error correction codinginformation, may be associated, either based explicitly on the commandsin the control information or implicitly based on other cross streamassociations.

The audiovisual information may be processed for presentation on themobile device. Processing the audiovisual information may includeprocessing the first audiovisual information and any associated errorcorrection coding information (such as, according to variousembodiments, might be contained in the first, second, and/or fifthpluralities of packets), and in some embodiments, processing the secondaudiovisual information and any associated error correction codinginformation (such as, according to various embodiments, might becontained in the second, fourth, and/or fifth pluralities of packets).In some embodiments, the first and second audiovisual streams (e.g., thefirst and fourth pluralities of packets) may be processed together, andwith all of the associated error correction coding information for bothstreams.

Processing the audiovisual information with the associated errorcorrection coding information may enable presentation of the audiovisualinformation even under adverse receiving conditions, e.g., if there isbackground noise in the transmission channel, or while the mobile deviceis moving rapidly and/or unpredictably. In addition, if the audiovisualinformation and/or the associated error correction coding informationare received separately, at different times and/or frequencies, this mayreduce the susceptibility of the mobile device to specific receptionissues such as burst noise and deep channel fading, because even if someof the error correction coding information is lost, or some partiallyredundant audiovisual information is lost, there may be enoughaudiovisual and/or error correction coding information received at othertimes and/or frequencies such that service at the mobile device may beuninterrupted.

Once the audiovisual information is processed for presentation, theprocessed audiovisual information may be presented on the mobile device.This may include presenting (e.g., displaying) video information on adisplay and/or presenting (e.g., playing) audio information on one ormore speakers.

The method for wirelessly receiving audiovisual information by a mobiledevice may be performed by a mobile device. The mobile device mayinclude an antenna for wirelessly receiving the packets, receiver logiccoupled to the antenna for associating the audiovisual and errorcorrection coding information, processing the audiovisual and errorcorrection coding information, and presenting the processed audiovisualinformation, and a display and one or more speakers on which theaudiovisual information may actually be presented.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of the preferred embodiment is consideredin conjunction with the following drawings, in which:

FIG. 1 illustrates a digital television broadcast system according toone embodiment;

FIG. 2 is a flowchart diagram illustrating a method for wirelesslytransmitting audiovisual information to a mobile device according to oneembodiment;

FIG. 3 is a flowchart diagram illustrating a method for wirelesslytransmitting audiovisual information to a mobile device according to oneembodiment;

FIG. 4 is a flowchart diagram illustrating a method for a mobile deviceto wirelessly receive and present audiovisual information;

FIG. 5 is a flowchart diagram illustrating a method for a mobile deviceto wirelessly receive and present audiovisual information;

FIG. 6 is an illustration of a four state systematic convolutionalencoder according to one embodiment;

FIG. 7 is an illustration of two basic puncturing patterns resulting incoding rates of R=½ and R=¼ according to one embodiment;

FIG. 8 is an illustration of several additional puncturing patternsresulting in coding rates of R=⅓, R=⅔, and R=⅘ according to oneembodiment;

FIG. 9 is a graph illustrating incremental coding gain and bandwidthoverhead for a variety of coding rates according to one embodiment;

FIG. 10 is a block diagram illustrating a block processor according toone embodiment;

FIG. 11 is a table listing payload length based on SCCC outer code modesfor each SCCC block mode/frame mode according to one embodiment;

FIG. 12 is a table listing SCCC output/input block lengths for variouscoding rates according to one embodiment;

FIG. 13 is an illustration of main stream augmentation as compared to aprior art solution according to one embodiment;

FIG. 14 is an illustration of an R=½ and an R=¼ coding scheme inaccordance with main stream augmentation according to one embodiment;

FIG. 15 is an illustration of an augmented service multiplex accordingto one embodiment;

FIGS. 16A and 16B are illustrations showing the organization of anaugmented stream according to one embodiment;

FIGS. 17A and 17B show syntax for a FIC channel according to oneembodiment;

FIG. 18 shows syntax for a TPC channel according to one embodiment;

FIG. 19 illustrates transmission diversity methods according to oneembodiment;

FIG. 20 is an illustration of a content stream with both time diverseand non-time diverse content according to one embodiment;

FIG. 21 is an illustration of two content streams on differentfrequencies, including both frequency diverse and non-frequency diversecontent according to one embodiment;

FIG. 22 illustrates complementary coding patterns suitable for nestedstream encoding according to one embodiment;

FIG. 23 illustrates equivalent R=½ canonical forms of a convolutionalencoder according to one embodiment;

FIG. 24 is a table defining the SCCC_Block_Mode_Extension term in theTPC syntax according to one embodiment;

FIG. 25 is a table showing how a convolutional encoder may define itsoutput in a way consistent with the syntax in the TPC channel defined inFIG. 24 according to one embodiment;

FIG. 26 illustrates stagger casted coding patterns according to oneembodiment.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to limit the invention to the particular formdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS FIG. 1—Digital TelevisionBroadcast System

FIG. 1 illustrates an exemplary broadcast system 100 according to oneembodiment of the invention. In one embodiment, the broadcast system maybe a digital television broadcast system. The broadcast system 100described herein, including the various methods described herein, may beused for broadcasting any of various types of data, includingaudiovisual information as well as other data.

As used herein, the term “audiovisual information” includes any ofvarious types of information or data that comprises video data and/oraudio data. The term “video data” includes motion video (such astelevision, movies, streaming video, etc., as well as image data, suchas JPEGs. The term “audiovisual information” further includes any ofvarious types of information or program instructions that, whenexecuted, cause a device to present video data (on a display) and/oraudio data (on speakers). For example, the term “audiovisualinformation” includes any of various types of gaming content (includingprogram instructions and/or data) that can be used and/or executed topresent gaming content (e.g., images, video, and/or audio) on apresentation device.

The broadcast system 100 and the various methods described herein aredescribed in the present application in the context of transmittingaudiovisual information for presentation by a receiving device, inparticular digital television. However, it is noted that the broadcastsystem 100 and the various methods described herein may be used fortransmission/reception of any of various types of data (e.g.,audiovisual information, email, files, text documents, seismic data,measurement data, weather data, etc.), with audiovisual informationbeing merely one representative example.

In one set of embodiments, the broadcast system may operate according tothe ATSC (Advanced Television Standards Committee) standard, e.g., using8-VSB modulation. Alternatively, the broadcast system may operateaccording to a modified version of the ATSC standard, or according toanother standard. For example, the Mobile/Handheld (M/H) modification ofthe ATSC standard is used for transmission of audiovisual informationfor moving receivers. The current M/H system transports M/H services inbursts alongside the main service stream encapsulated in NULL packetsconsistent with the methods prescribed for E-VSB service multiplexing.The system uses serial concatenated convolutional coding (SCCC) foradditional robustness. To aid M/H reception, the existing M/H systemsupplements the base 8-VSB transport with the addition of extra trainingmultiplexed with the mobile packet data in such a way that the trainingdata appears in contiguous bytes (2 full segments per training) attransmission. Thus, when it is available, a receiver can utilize thisadditional training information to update its equalizer in order totrack fast moving channel conditions. Specific examples of theembodiments disclosed herein may be based on, or include portions of theM/H modification to the ATSC standard, and may also include furthervariations and modifications to M/H and the ATSC standard. However, theembodiments related to transmission of audiovisual information disclosedherein are not necessarily limited to use with the ATSC or M/H systems,and may be equally applicable for transmission of audiovisualinformation in accordance with other standards and/or modulationsschemes, such as DVB-T/H, ISDB-T, DMB-T/H, etc.

As shown, the system 100 comprises a transmission system (or transmitsystem) 102, one or more mobile devices 112 (e.g., mobile devices112A-112D), and at least one stationary device 114. As noted above FIG.1 is exemplary only, e.g., an exemplary system may comprise one or moretransmission systems 102, a plurality of mobile devices 112, and aplurality of stationary devices 114.

The transmission system 102 is configured to transmit audiovisualinformation to the one or more mobile devices 112 in a wireless manner.More particularly, the transmission system 102 may be configured totransmit digital television signals/channels to the mobile devices 112.The mobile devices 112 may receive and present the audiovisualinformation, e.g., receive and present the digital televisionsignals/channels. The transmission system 102 may also be configured totransmit audiovisual information to the stationary device 114 (e.g.,stationary television) in a wireless manner. The transmission system 102is also configured to transmit audiovisual information to the one ormore stationary devices 114, e.g., televisions.

For the sake of convenience, embodiments of the invention are describedherein with respect to reception by mobile devices 112. However, thevarious embodiments of the invention described herein may also of coursebe used for reception by stationary devices. For example, one embodimentof the invention provides for reception of additional error correctioninformation by stationary devices 114 for the purpose of enhancing therobustness of the terrestrial broadcast. Thus any of the various methodsdescribed herein may be utilized with either mobile devices 112 orstationary devices 114, or both, as desired.

The transmission system 102 comprises a transmitter 106 as well astransmit logic 104 coupled to the transmitter 106. The transmit logic104 may comprise any of various types of logic, such as one or morecomputer systems (with accompanying software), digital logic, analoglogic, programmable gate arrays, etc., or combinations thereof. Thetransmit logic 104 is adapted for receiving and/or storing audiovisualinformation (e.g., television data) and for generating packetscontaining the audiovisual information. The transmit logic 104 maygenerate packets according to any of various standards, such as the ATSC(Advanced Television Standards Committee) standard, e.g., using 8-VSBmodulation. The transmission system 102 may use other modulationschemes, such as DVB-T/H, ISDB-T, DMB-T/H, etc. The transmit logic 104is also adapted for generating error correction coding information. Forexample, the transmit logic 104 may be configured to encode data withany of various types of error correction techniques, including (but notlimited to): convolutional coding (such as trellis encoding), blockcoding (such as Reed-Solomon encoding), or other error correctiontechniques. The transmit logic 104 may be configured to encode data withmore than one error correction technique. The transmit logic 104 is alsoconfigured to generate packets containing control information asdescribed herein. In one embodiment, one or more of the digitaltelevision channels are intended for stationary receivers, such astelevisions. One or more of the digital television channels may also beintended for mobile and/or handheld (M/H) (referred to collectivelyherein as “mobile”) devices 112. In one embodiment, one or more of thedigital television channels may be intended for either stationaryreceivers or mobile devices.

As described herein, for digital television channels intended for mobiledevices 112 (and possibly for all channels, e.g., channels intended forstationary devices 114 and/or mobile devices 112), the transmit logic104 may be configured to generate packets containing error correctioncoding information. For example, the transmit logic 104 may generateerror correction coding information for audiovisual information, and maytransmit the error correction coding information in a separate packet(or packets) than the audiovisual information, with another packet (orpackets) containing control information for associating the errorcorrection coding information with the audiovisual information. Thus, areceiver (such as a stationary receiver) which does not require or isnot configured to use the error correction coding information may ignorethe error correction coding information packet and simply receive theaudiovisual information as a normal audiovisual stream, while a receiver(such as a mobile device) which does require additional error correctioncoding information and is configured to use the error correction codinginformation may associate the error correction coding information withthe audiovisual information (e.g., based on the control information) andthereby achieve a more robust system. Furthermore, the controlinformation can be used by the transmit logic 104 to generate andtransmit new types of error correction coding that is usable by thereceiver.

The mobile devices 112 may be any of various types of devices, such asportable computer systems (laptops) 112A, wireless telephones 112B(e.g., Blackberrys, iPhones, etc.), personal digital assistants 112C,television equipment 112D configured in vehicles, and other types ofportable devices capable of displaying received audiovisual information.

The mobile devices 112 are configured to wirelessly receive (e.g., withan antenna) the packets transmitted by the transmitter 106, includingthe packets containing audiovisual information, the packets containingerror correction coding information, and the packets containing controlinformation. A respective mobile device 112 may also include receiverlogic for processing the received audiovisual information, as well as adisplay for presenting video information and one or more speakers forpresenting audio information. Thus each of the mobile devices 112 mayinclude television-like capabilities for presenting received televisionchannels as described herein.

The stationary devices 114 may be any of various types of devices thatare intended to be placed at a fixed location (referred to as stationaryor “non-mobile”), such as conventional televisions, e.g., liquid crystaldisplays (LCD displays), plasma displays, etc.

FIG. 2—Transmit Flowchart

FIG. 2 is a flowchart depicting a method for transmitting audiovisualinformation. The method may be performed by a transmission system suchas described above and shown in FIG. 1, e.g., a system includingtransmit logic and a transmitter. The audiovisual information may be forreception by mobile devices; alternatively, the audiovisual informationmay be for reception by stationary devices, or, both mobile andstationary devices. It should be noted that, according to variousembodiments, one or more of the steps may be omitted, repeated, orperformed in a different order than shown in FIG. 2 and described below.

In 202, a first plurality of packets including audiovisual informationmay be generated. The packets containing audiovisual information mayinclude one or more content streams intended for mobile and/orstationary devices. In one embodiment, the packets may be generatedaccording to the ATSC (Advanced Television Standards Committee) DTV(digital television) standard containing one or more digital televisionchannels intended for stationary receivers (e.g., televisions);alternatively, or in addition, the packets may contain one or moredigital television channels intended for mobile/handheld (M/H)receivers.

Generation of the packets containing audiovisual information maycomprise various steps, such as encoding the audio and video data (e.g.,using MPEG-2 encoding), applying forward error correction, generatingappropriate packet headers and control information, etc. The forwarderror correction may take any number of forms, including Reed-Solomon(RS) encoding, Trellis encoding, cyclic redundancy codes (CRCs), or anyother form of error correction coding, including a combination ofmultiple methods.

In 204, a second plurality of packets including error correction codinginformation for the audiovisual information may be generated. The errorcorrection coding information in the second plurality of packets may beany type of error correction coding, as desired; thus, it may be thesame as or different than the error correction coding information in thefirst plurality of packets. The error correction information in thesecond plurality of packets may be supplemental to any error correctioninformation in the first plurality of packets. In one embodiment, boththe first and second pluralities of packets may include codinginformation from a four state convolutional encoder, such as shown inFIG. 6 and described with respect thereto.

In a specific embodiment, the packets including the audiovisualinformation may include a systematic (i.e., including the input(audiovisual) data) coding scheme, while the packets including theadditional error correction coding information may include acomplementary non-systematic (i.e., including only coded (errorcorrection) data) coding scheme. This is referred to herein as ‘mainstream augmentation’ and is described in more detail according to anexemplary embodiment with respect to FIGS. 13 and 14.

In another embodiment, the packets including the additional errorcorrection information may include more than one complementarynon-systematic coding scheme. In other words, there may be a systematiccoding scheme in the audiovisual stream and two or more error correctioncoding patterns, complementary to each other and to the systematiccoding scheme in the audiovisual stream, in a separate error correctionstream. This is referred to herein as ‘nested stream encoding’ and isdescribed in more detail according to an exemplary embodiment withrespect to FIG. 22.

In some embodiments, two or more of these audiovisual and/or errorcorrection streams may be separated in time and/or frequency. In otherwords, one stream may be sent at one time on a certain frequency, whileanother stream may be sent at a specified time delay and/or on adifferent frequency. This may be used in combination with any of mainstream augmentation, nested stream encoding, or stagger casting (whichwill be defined later), as desired. This is referred to herein as‘transmission diversity’ and is explained more fully with respect toFIGS. 19-21.

In 206, control information including commands for associating the errorcorrection coding with the audiovisual information may be generated. Thecontrol information may indicate which error correction codinginformation is to be associated with which audiovisual information, andmay indicate where in the pluralities of packets the error correctioncoding information and the audiovisual information to be associated areto be found. In other words, the control information may be usable by amobile device receiving the first plurality of packets and the secondplurality of packets to determine which error correction information inthe second plurality of packets to use to process a particular block ofaudiovisual information from the first plurality of packets. The controlinformation may be in any number of formats, or may be divided intomultiple formats. For example, in the ATSC M/H system, there may be aFast Information Channel (FIC) and a Transmission Protocol Channel(TPC). Each of these may include part of the control information. In oneembodiment, the presence of an augmented main stream (e.g., the presenceof additional error correction information in the second plurality ofpackets) may be signaled in the TPC, while the location, length, andform (and/or other information) of the additional error correction maybe signaled in the FIC. Specific embodiments of TPC and FIC signalingand syntax are shown in FIGS. 16-18 and described with respect thereto,however, it should be noted that these are exemplary only, and otherkinds of control information (or other syntax for the TPC and/or theFIC) for associating the error correction coding information in thesecond plurality of packets with the audiovisual information in thefirst plurality of packets are also possible. If any of the informationto be associated is separated in time and/or frequency (i.e., iftransmission of the information is time and/or frequency diverse), thecontrol information may also indicate this.

In general, the use of control information to associate separate streamsof information (audiovisual, error correction, or otherwise) for usetogether is referred to herein as ‘cross stream association’. Crossstream association is an underlying concept to main stream augmentation,nested stream encoding, and stagger casting (as will be defined later),and allows for planned and systematic use of transmission diversity, inparticular in combination with these cases, in order to achieve asignificant improvement in packetized data transmission, and inparticular packetized transmission of audiovisual information for mobiledevices.

In 208, a third plurality of packets including the control informationmay be generated. The control information may be packetized in a similarway as the first plurality of packets and the second plurality ofpackets. In an alternative embodiment, some or all of the controlinformation may be included in either the first plurality of packets, orthe second plurality of packets, or both, rather than separately in athird plurality of packets. However, in some embodiments, sending thecontrol information separately may be beneficial, e.g., in the casewhere both stationary devices and mobile devices should be able to usethe audiovisual stream, but stationary devices might not be able to usethe control information; in this case, sending the control informationwith the audiovisual information could potentially render theaudiovisual stream unusable for the stationary devices.

FIGS. 2-5 describe an embodiment where the control data is placed in athird (or fifth) plurality of packets, i.e., in packets separate fromthose containing the audiovisual information and the error correctioninformation. However, as noted above the control data may be placed ineither the first plurality or second plurality of packets, or both (inthe case of FIGS. 2 and 4). In the case of FIGS. 3 and 5, the controldata may be placed in any one or more of the first—fourth plurality ofpackets, as desired.

In 210, the plurality of packets, including the first, second, and(possibly) third pluralities of packets, may be transmitted.Transmission of these pluralities of packets may comprise multiplexingthe first, second, and third pluralities of packets (multiplexing thefirst, second and third streams). Multiplexing of these differentpackets or streams may be performed based on a ratio of the relativebandwidth allocations of the respective pluralities of packets (orstreams). In one embodiment corresponding to continuous mode,multiplexing these different packet streams comprises ordering thepackets to distribute them evenly according to their relative bandwidth.In another embodiment corresponding the burst mode, the different packetstreams are aggregated in separate bursts preceded by controlinformation (aggregated in its own burst) to indicate the start positionof the remaining bursts. The multiplexing may operate to reducetransmission overhead. In one embodiment, the transmission methodtransmits size information regarding the bandwidth allocations of thevarious packet streams, wherein the size information is useable at thereceiver to demultiplex the received packet streams.

FIG. 3—Extended Transmit Flowchart

FIG. 3 is a flowchart depicting a method for transmitting audiovisualinformation in multiple streams. The method may be performed by atransmission system such as described above and shown in FIG. 1, e.g., asystem including transmit logic and a transmitter. The audiovisualinformation may be for reception by mobile devices; alternatively, theaudiovisual information may be for reception by stationary devices, orboth mobile and stationary devices. It should be noted that, accordingto various embodiments, one or more of the steps may be omitted,repeated, or performed in a different order than shown in FIG. 2 anddescribed below.

In 302, a first plurality of packets including first audiovisualinformation may be generated. The packets containing the firstaudiovisual information may include one or more content streams intendedfor mobile and/or stationary devices. In one embodiment, the packets maybe generated according to the ATSC (Advanced Television StandardsCommittee) DTV (digital television) standard containing one or moredigital television channels intended for stationary receivers (e.g.,televisions); alternatively, or in addition, the packets may contain oneor more digital television channels intended for mobile/handheld (M/H)receivers.

Generation of the packets containing the first audiovisual informationmay comprise various steps, such as encoding the audio and video data(e.g., using MPEG-2 encoding), applying forward error correction,generating appropriate packet headers and control information, etc. Theforward error correction may take any number of forms, includingReed-Solomon (RS) encoding, Trellis encoding, cyclic redundancy codes(CRCs), or any other form of error correction coding, including acombination of multiple methods.

In 304, a second plurality of packets including first error correctioncoding information for the first audiovisual information may begenerated. The first error correction coding information in the secondplurality of packets may be any type of error correction coding, asdesired; thus, it may be the same as or different than the errorcorrection coding information in the first plurality of packets. Theerror correction coding information in the second plurality of packetsmay be supplemental to any error correction information in the firstplurality of packets. In one embodiment, both the first and secondpluralities of packets may include coding information from a four stateconvolutional encoder, such as shown in FIG. 6 and described withrespect thereto.

In a specific embodiment, the packets including the first audiovisualinformation may include a systematic coding scheme, while the packetsincluding the first error correction coding information may include acomplementary non-systematic coding scheme. In other words, the firsterror correction coding information may be an augmentation to the mainstream (e.g., the first audiovisual information).

In another embodiment, the packets including the first error correctioninformation may include more than one complementary non-systematiccoding scheme. In other words, there may be a systematic coding schemein the first audiovisual stream and two or more error correction codingpatterns, complementary to each other and to the systematic codingscheme in the audiovisual stream, in a separate error correction stream(or streams). In other words, the first error correction codinginformation may be encoded in multiple nested streams.

In some embodiments, two or more of these audiovisual and/or errorcorrection streams may be separated in time and/or frequency. In otherwords, one stream may be sent at one time on a certain frequency, whileanother stream may be sent at a specified time delay and/or on adifferent frequency. This may be used in combination with any of mainstream augmentation, nested stream encoding, or stagger casting (whichwill be defined below), as desired. In other words, the multiple streamsof audiovisual and/or error correction coding information may beconfigured for transmission diversity.

In 306, a third plurality of packets including second audiovisualinformation may be generated. The second audiovisual information may becomplementary to, partially complementary to and partially overlappingwith, or completely overlapping with the first audiovisual information.In general, the first and second audiovisual information may benefitfrom being associated with each other; for example, the first and secondaudiovisual information may build on each other to produce a more robustsignal.

In 308, a fourth plurality of packets including second error correctioncoding information for the second audiovisual information may begenerated. The second error correction coding information may be anytype of error correction coding, as desired; thus, it may be the same asor different than the error correction coding information in the thirdplurality of packets. The error correction information in the fourthplurality of packets may be supplemental to any error correctioninformation in the third plurality of packets. In one embodiment, boththe third and fourth pluralities of packets may include codinginformation from a four state convolutional encoder, such as shown inFIG. 6 and described with respect thereto.

In a specific embodiment, the third plurality of packets may include asystematic coding scheme, while the fourth plurality of packets mayinclude a complementary non-systematic coding scheme. Thus, in someembodiments, the first audiovisual information may be the input data ina systematic coding scheme, while the second audiovisual information maybe complementary or overlapping input data in a complementary oroverlapping coding scheme. The coded data (error correction information)for the complementary or overlapping coding schemes may becomplementary.

The audiovisual streams (first and third pluralities of packets) mayinclude this complementary error correction information; alternatively,or in addition, the complementary error correction coding informationmay be the error correction information in the second and fourthpluralities of packets. In some embodiments, the error correction codinginformation in the second and/or fourth packets may also be systematiccoding schemes. Thus, in some embodiments, there may be a number ofstreams of overlapping or complementary audiovisual streams withcomplementary error correction coding information. In another possibleembodiment, the error correction information in the second and fourthpluralities of packets may be non-systematic, but still complementary.In this case, there would be nested stream encoding in addition to themultiple complementary/overlapping audiovisual streams.

In other words, the audiovisual data may be either overlapping orcomplementary, while the error correction information may becomplementary. In this way, it may be possible for a device to receiveeither the first packets with the first audiovisual information, or thethird packets with the second audiovisual information, and use theaudiovisual information even if the complementary/overlappingaudiovisual information is not received. On the other hand, if all ofthe complementary/overlapping audiovisual information is received, thecomplementary coding data may provide additional robustness, allowingfor a lower receive threshold. The case where multiple streams withoverlapping audiovisual data with complementary error correctioninformation are transmitted is referred to herein as ‘stagger casting’and is described in further detail as it could be implemented in oneembodiment with respect to FIGS. 23-25. Transmission diversitytechniques may also be used in accordance with stagger casting; in otherwords, each of the complementary or overlapping audiovisual streams maybe sent at a specific time delay or on a different frequency from oneanother. As noted above, nested stream encoding can also be used incombination with stagger casting. It should further be noted that, in asense, nested stream encoding and stagger casting can both be consideredspecial cases of main stream augmentation.

In 310, control information including commands for associating the firsterror correction coding information with the first audiovisualinformation and commands for associating the second error correctioncoding information with the second audiovisual information may begenerated. The control information may indicate which error correctioncoding information is to be associated with which audiovisualinformation, and may indicate where in the pluralities of packets theerror correction coding information and the audiovisual information tobe associated are to be found. In other words, the control informationmay be usable by a mobile device receiving the first plurality ofpackets and the second plurality of packets to determine which errorcorrection information in the second plurality of packets to use toprocess a particular block of audiovisual information from the firstplurality of packets. The commands in the control information may alsoindicate if multiple blocks of audiovisual information are to beassociated with each other, e.g., if the first and third pluralities ofpackets contain complementary or overlapping information. Similarly, theerror correction coding associated with each audiovisual stream may beassociated with another (complementary or overlapping) audiovisualstream, either explicitly by the commands in the control information, orinherently due to the association of the complementary or overlappingaudiovisual streams with each other. In short, the commands in thecontrol information may effectively form a cross stream association.

The control information may be in any number of formats, or may bedivided into multiple formats. For example, in the ATSC M/H system,there may be a Fast Information Channel (FIC) and a TransmissionProtocol Channel (TPC). Each of these may include part of the controlinformation. In one embodiment, the presence of an augmented main stream(e.g., the presence of additional error correction information in thesecond plurality of packets) may be signaled by a command in the TPC,while the location, length, and form (and/or other information) of theadditional error correction may be signaled by commands in the FIC.Specific embodiments of TPC and FIC signaling and syntax are shown inFIGS. 16-18 and described with respect thereto, however, it should benoted that these are exemplary only, and other kinds of controlinformation (or other syntax for the TPC and/or the FIC) for associatingthe error correction coding information in the second plurality ofpackets with the audiovisual information in the first plurality ofpackets are also possible. If any of the information to be associated isseparated in time and/or frequency (i.e., if transmission of theinformation is time and/or frequency diverse), the control informationmay also indicate this.

In 312, a fifth plurality of packets including the control informationmay be generated. The control information may be packetized in a similarway as the first plurality of packets (and the other pluralities ofpackets). In an alternative embodiment, some or all of the controlinformation may be included in one or more of the other pluralities ofpackets, rather than separately in a fifth plurality of packets.However, in some embodiments, sending the control information separatelymay be beneficial, e.g., in the case where both stationary devices andmobile devices should be able to use the audiovisual stream(s), butstationary devices might not be able to use the control information; inthis case, sending the control information with the audiovisualinformation could potentially render the audiovisual stream unusable forthe stationary devices.

In 314, the plurality of packets, including the first, second, third,fourth, and fifth pluralities of packets may be transmitted.Transmission of these pluralities of packets may comprise multiplexingthe first, second, third, fourth, and fifth pluralities of packets(multiplexing the first, second, and third streams). Multiplexing ofthese different packets or streams may be performed based on a ratio ofthe relative bandwidth allocations of the respective pluralities ofpackets (or streams). In one embodiment corresponding to continuousmode, multiplexing these different packet streams comprises ordering thepackets to distribute them evenly according to their relative bandwidth.In another embodiment corresponding the burst mode, the different packetstreams are aggregated in separate bursts preceded by controlinformation (aggregated in its own burst) to indicate the start positionof the remaining bursts. The multiplexing may operate to reducetransmission overhead. In one embodiment, the transmission methodtransmits size information regarding the bandwidth allocations of thevarious packet streams, wherein the size information is useable at thereceiver to demultiplex the received packet streams.

FIG. 4—Receive Flowchart

FIG. 4 is a flowchart depicting a method for receiving and presentingaudiovisual information. The method may be performed by a mobile devicesuch as described above and shown in FIG. 1, e.g., portable computersystems (laptops), wireless telephones (e.g., Blackberrys, iPhones,etc.), personal digital assistants, television equipment configured invehicles, and other types of portable devices capable of displayingreceived audiovisual information. Alternatively, in some embodiments,the method may be performed by a stationary device, such as also shownin FIG. 1 and described above, e.g., a conventional television, such asliquid crystal display (LCD display) television, a plasma displaytelevision, etc. It should be noted that, according to variousembodiments, one or more of the steps may be omitted, repeated, orperformed in a different order than shown in FIG. 2 and described below.

In 402, a first plurality of packets including audiovisual informationmay be received. The packets containing audiovisual information mayinclude one or more content streams intended for mobile and/orstationary devices. In one embodiment, the packets may be generatedaccording to the ATSC (Advanced Television Standards Committee) DTV(digital television) standard containing one or more digital televisionchannels intended for stationary receivers (e.g., televisions);alternatively, or in addition, the packets may contain one or moredigital television channels intended for mobile/handheld (M/H)receivers. The packets containing audiovisual information may alsoinclude error correction coding, such as forward error correction; thismay take any number of forms, including but not limited to RS encoding,Trellis encoding, CRCs, or other forms of error correction coding,including a combination of multiple methods.

In 404, a second plurality of packets including error correction codinginformation for the audiovisual information may be received. The errorcorrection coding information in the second plurality of packets may beany type of error correction coding, as desired; thus, it may be thesame as or different than the error correction coding information in thefirst plurality of packets. The error correction information in thesecond plurality of packets may be supplemental to any error correctioninformation in the first plurality of packets. In one embodiment, boththe first and second pluralities of packets may include codinginformation from a four state convolutional encoder, such as shown inFIG. 6 and described with respect thereto.

In a specific embodiment, the packets including the audiovisualinformation may include a systematic (i.e., including the input(audiovisual) data) coding scheme, while the packets including theadditional error correction coding information may include acomplementary non-systematic (i.e., including only coded (errorcorrection) data) coding scheme. In other words, the error correctioncoding information may be an augmentation to the main stream (e.g., theaudiovisual information).

In another embodiment, the packets including the additional errorcorrection information may include more than one complementarynon-systematic coding scheme. In other words, there may be a systematiccoding scheme in the audiovisual stream and two or more error correctioncoding patterns, complementary to each other and to the systematiccoding scheme in the audiovisual stream, in a separate error correctionstream. In other words, the error correction coding information may beencoded in multiple nested streams.

In some embodiments, two or more of these audiovisual and/or errorcorrection streams may be separated in time and/or frequency. In otherwords, one stream may be received at one time on a certain frequency,while another stream may be received at a specified time delay and/or ona different frequency. In other words, there may be transmissiondiversity between the audiovisual information and the error correctioncoding information.

In 406, a third plurality of packets including control information whichincludes commands for associating the error correction coding with theaudiovisual information may be received. The control information mayindicate which error correction coding information is associated withwhich audiovisual information, and may indicate where in the pluralitiesof packets the error correction coding information and the associatedaudiovisual information are to be found. In other words, the controlinformation may be usable by the mobile device to determine which errorcorrection information in the second plurality of packets to use toprocess a particular block of audiovisual information from the firstplurality of packets. In short, the commands in the control informationmay effectively form a cross stream association.

The control information may be in any number of formats, or may bedivided into multiple formats. For example, in the ATSC M/H system,there may be a Fast Information Channel (FIC) and a TransmissionProtocol Channel (TPC). Each of these may include part of the controlinformation. In one embodiment, the presence of an augmented main stream(e.g., the presence of additional error correction information in thesecond plurality of packets), or nested streams, may be signaled in theTPC, while the location, length, and form (and/or other information) ofthe additional error correction may be signaled in the FIC. Specificembodiments of TPC and FIC signaling and syntax are shown in FIGS. 16-18and described with respect thereto, however, it should be noted thatthese are exemplary only, and other kinds of control information (orother syntax for the TPC and/or the FIC) for associating the errorcorrection coding information in the second plurality of packets withthe audiovisual information in the first plurality of packets are alsopossible. If any of the information to be associated is separated intime and/or frequency (i.e., if transmission of the information is timeand/or frequency diverse), the control information may also indicatethis.

In 408, the error correction coding information may be associated withthe audiovisual information based on the control information. The mobiledevice may associate specific error correction coding information with aspecific portion of audiovisual information based on the commands in thecontrol information, e.g., based on the TPC and FIC commands.

In 410, the audiovisual information, including the error correctioncoding information associated with the audiovisual information, may beprocessed. Processing the audiovisual information may include performingthe inverse of any steps taken in preparing the data for transmissionand/or packetizing the data, e.g., demultiplexing the data, decoding anyerror correction information, decoding the audio and video data, etc.Decoding the error correction information may include both decoding anyerror correction information received in the first plurality of packets(i.e., with the audiovisual information), and any error correctioninformation received in the second plurality of packets (i.e., separatedfrom the audiovisual information) that is associated with theaudiovisual information based on the commands in the controlinformation.

In 412, the processed audiovisual information may be presented.Presenting the processed audiovisual information may include presentingvideo information on a display and/or presenting audio information onone or more speakers.

FIG. 5—Extended Receive Flowchart

FIG. 5 is a flowchart depicting a method for receiving and presentingaudiovisual information. The method may be performed by a mobile devicesuch as described above and shown in FIG. 1, e.g., portable computersystems (laptops), wireless telephones (e.g., Blackberrys, iPhones,etc.), personal digital assistants, television equipment configured invehicles, and other types of portable devices capable of displayingreceived audiovisual information. Alternatively, in some embodiments,the method may be performed by a stationary device, such as also shownin FIG. 1 and described above, e.g., a conventional television, such asliquid crystal display (LCD display) television, a plasma displaytelevision, etc. It should be noted that, according to variousembodiments, one or more of the steps may be omitted, repeated, orperformed in a different order than shown in FIG. 2 and described below.

In 502, a first plurality of packets including first audiovisualinformation may be received. The packets containing the firstaudiovisual information may include one or more content streams intendedfor mobile and/or stationary devices. In one embodiment, the packets maybe generated according to the ATSC (Advanced Television StandardsCommittee) DTV (digital television) standard containing one or moredigital television channels intended for stationary receivers (e.g.,televisions); alternatively, or in addition, the packets may contain oneor more digital television channels intended for mobile/handheld (M/H)receivers. The packets containing the first audiovisual information mayalso include error correction coding, such as forward error correction;this may take any number of forms, including but not limited to RSencoding, Trellis encoding, CRCs, or other forms of error correctioncoding, including a combination of multiple methods.

In 504, a second plurality of packets including first error correctioncoding information for the first audiovisual information may bereceived. The first error correction coding information may be any typeof error correction coding, as desired; thus, it may be the same as ordifferent than the error correction coding information (if any) in thefirst plurality of packets. The first error correction information maybe supplemental to any error correction information in the firstplurality of packets. In one embodiment, both the first and secondpluralities of packets may include coding information from a four stateconvolutional encoder, such as shown in FIG. 6 and described withrespect thereto.

In a specific embodiment, the packets including the first audiovisualinformation may include a systematic coding scheme, while the packetsincluding the first error correction coding information may include acomplementary non-systematic coding scheme. In other words, the firsterror correction coding information may be an augmentation to the mainstream (e.g., the first audiovisual information).

In another embodiment, the packets including the additional errorcorrection information may include more than one complementarynon-systematic coding scheme. In other words, there may be a systematiccoding scheme in the audiovisual stream and two or more error correctioncoding patterns, complementary to each other and to the systematiccoding scheme in the audiovisual stream, in a separate error correctionstream. In other words, the first error correction coding informationmay be encoded in multiple nested streams.

In some embodiments, two or more of these audiovisual and/or errorcorrection coding patterns may be separated in time and/or frequency. Inother words, one stream may be received at one time on a certainfrequency, while another stream may be received at a specified timedelay and/or on a different frequency. In other words, there may betransmission diversity between the audiovisual information and the errorcorrection coding information.

In 506, a third plurality of packets including second audiovisualinformation may be received. The second audiovisual information may becomplementary to, partially complementary to and partially overlappingwith, or completely overlapping with the first audiovisual information.In general, the first and second audiovisual information may benefitfrom being associated with each other; for example, the first and secondaudiovisual information may build on each other to produce a more robustsignal.

In 508, a fourth plurality of packets including second error correctioncoding information for the second audiovisual information may bereceived. The second error correction coding information may be any typeof error correction coding, as desired; thus, it may be the same as ordifferent than the error correction coding information in the thirdplurality of packets. The error correction information in the fourthplurality of packets may be supplemental to any error correctioninformation in the third plurality of packets. In one embodiment, boththe third and fourth pluralities of packets may include codinginformation from a four state convolutional encoder, such as shown inFIG. 6 and described with respect thereto.

In a specific embodiment, the third plurality of packets may include asystematic coding scheme, while the fourth plurality of packets mayinclude a complementary non-systematic coding scheme. Thus, in someembodiments, the first audiovisual information may be the input data ina systematic coding scheme, while the second audiovisual information maybe complementary or overlapping input data in a complementary oroverlapping coding scheme. The coded data (error correction information)for the complementary or overlapping coding schemes may becomplementary.

The audiovisual streams (first and third pluralities of packets) mayinclude this complementary error correction information; alternatively,or in addition, the complementary error correction coding informationmay be the error correction information in the second and fourthpluralities of packets. In some embodiments, the error correction codinginformation in the second and/or fourth packets may also be systematiccoding schemes. Thus, in some embodiments, there may be a number ofstreams of overlapping or complementary audiovisual streams withcomplementary error correction coding information. In another possibleembodiment, the error correction information in the second and fourthpluralities of packets may be non-systematic, but still complementary.In this case, there would be nested stream encoding in addition to themultiple complementary/overlapping audiovisual streams.

In other words, the audiovisual data may be either overlapping orcomplementary, while the error correction information may becomplementary. In this way, it may be possible for a device to receiveeither the first packets with the first audiovisual information, or thethird packets with the second audiovisual information, and use theaudiovisual information even if the complementary/overlappingaudiovisual information is not received. On the other hand, if all ofthe complementary/overlapping audiovisual information is received, thecomplementary coding data may provide additional robustness, allowingfor a lower receive threshold. The case where multiple streams withoverlapping audiovisual data with complementary error correctioninformation are transmitted is referred to herein as ‘stagger casting’and is described in further detail as it could be implemented in oneembodiment with respect to FIGS. 23-25. Transmission diversitytechniques may also be used in accordance with stagger casting; in otherwords, each of the complementary or overlapping audiovisual streams maybe sent at a specific time delay or on a different frequency from oneanother. As noted above, nested stream encoding can also be used incombination with stagger casting. It should further be noted that, in asense, nested stream encoding and stagger casting can both be consideredspecial cases of main stream augmentation.

In 510, a fifth plurality of packets including control information whichincludes commands for associating the first error correction codinginformation with the first audiovisual information and commands forassociating the second error correction coding information with thesecond audiovisual information may be received. The control informationmay indicate which error correction coding information is to beassociated with which audiovisual information, and may indicate where inthe pluralities of packets the error correction coding information andthe audiovisual information to be associated are to be found. In otherwords, the control information may be usable by the mobile device todetermine which error correction information in the second plurality ofpackets to use to process a particular block of audiovisual informationfrom the first plurality of packets. The commands in the controlinformation may also indicate if multiple blocks of audiovisualinformation are to be associated with each other, e.g., if the first andthird pluralities of packets contain complementary or overlappinginformation. Similarly, the error correction coding associated with eachaudiovisual stream may be associated with another (complementary oroverlapping) audiovisual stream, either explicitly by the commands inthe control information, or inherently due to the association of thecomplementary or overlapping audiovisual streams with each other. Inshort, the commands in the control information may effectively form across stream association.

The control information may be in any number of formats, or may bedivided into multiple formats. For example, in the ATSC M/H system,there may be a Fast Information Channel (FIC) and a TransmissionProtocol Channel (TPC). Each of these may include part of the controlinformation. In one embodiment, the presence of an augmented main stream(e.g., the presence of additional error correction information in thesecond plurality of packets) may be signaled by a command in the TPC,while the location, length, and form (and/or other information) of theadditional error correction may be signaled by commands in the FIC.Specific embodiments of TPC and FIC signaling and syntax are shown inFIGS. 16-18 and described with respect thereto, however, it should benoted that these are exemplary only, and other kinds of controlinformation (or other syntax for the TPC and/or the FIC) for associatingthe error correction coding information in the second plurality ofpackets with the audiovisual information in the first plurality ofpackets are also possible. If any of the information to be associated isseparated in time and/or frequency (i.e., if transmission of theinformation is time and/or frequency diverse), the control informationmay also indicate this.

In 512, the first error correction coding information may be associatedwith the first audiovisual information based on the control information,while in 514, the second error correction coding information may beassociated with the second audiovisual information based on the controlinformation. The mobile device may associate specific error correctioncoding information with a specific portion of audiovisual informationbased on the commands in the control information, e.g., based on the TPCand FIC commands.

In 516, the first and second audiovisual information, including thefirst and second error correction coding information associated with thefirst and second audiovisual information, may be processed. Processingthe audiovisual information may include performing the inverse of anysteps taken in preparing the data for transmission and/or packetizingthe data, e.g., demultiplexing the data, decoding any error correctioninformation, decoding the audio and video data, etc. Decoding the errorcorrection information may include both decoding any error correctioninformation received in the first plurality of packets (i.e., with thefirst audiovisual information), and any error correction informationreceived in the second plurality of packets (i.e., separated from thefirst audiovisual information) that is associated with the firstaudiovisual information based on the commands in the controlinformation. Similarly, any error correction coding information receivedin the third plurality of packets may be decoded along with anyassociated error correction coding information received in the fourthplurality of packets. In some embodiments, because of the (explicit orimplicit) association of the second error correction coding informationwith the first audiovisual information, the second error correctioncoding information may be used in processing the first audiovisualinformation. Similarly, the first error correction information may beused in processing the second audiovisual information. Likewise, if thefirst and second audiovisual information include complementary errorcorrection coding information, they may be processed together. Suchcombinations of associated error correction coding information duringprocessing may result in a stronger, more robust audiovisual stream forpresentation, and/or may make it possible to receive and presentaudiovisual information at the mobile device even under adversereceiving conditions.

In 518, the processed audiovisual information may be presented.Presenting the processed audiovisual information may include presentingvideo information on a display and/or presenting audio information onone or more speakers.

FIG. 6—Four State Convolutional Outer Code

FIG. 6 illustrates a systematic convolutional encoding scheme with R=⅕and K=3 and a corresponding coding structure. Based on this commonstructure, a variety of puncturing patterns can be used to derivemultiple rates (R=n/k, where there are n-input bits and k-output bits).Various puncturing patterns can also be used in accordance with crossstream association to create complementary coding patterns separated intime or frequency. While FIG. 6 shows a particular convolutionalencoding scheme which will be referred to for convenience herein, itshould be noted that other encoding schemes (e.g., other convolutionalencoding schemes or other types of error correction coding schemes) maybe used in addition or instead of the scheme shown in FIG. 6 anddescribed herein.

FIG. 7—Basic Puncturing Patterns, Rates ½, ¼

FIG. 7 illustrates two basic puncturing patterns that can be used withthe convolutional encoding scheme shown in FIG. 6. As shown, for R=½, 2bits are transmitted for every input, while, for R=¼, 4 bits aretransmitted for every input bit. Given that the outer convolutionalencoder is systematic, the input bits are passed to the outputunmodified, and reordered in bit-tuples along with the coded data, asshown in FIG. 7.

FIG. 8—Additional Puncturing Patterns, Rates ⅓, ⅔, ⅘

FIG. 8 illustrates several additional puncturing patterns that can beused with the convolutional encoding scheme shown in FIG. 6. As shown,the various puncturing patterns can be used to produce rates of ⅓, ⅔, or⅘. Other puncturing patterns, producing other rates, are also possible.

FIG. 9—Incremental Gain vs. Overhead

FIG. 9 is a graph depicting the incremental gain (i.e., the additionalgain over the previous coding rate) and the associated percentage ofbandwidth thereby dedicated to overhead for a variety of coding rates.The availability of a number of rates opens up the possibility ofdynamically changing the coding rate used to encode data. For example,depending on the transmission and/or reception conditions, it mayvariously be desirable to use a lower coding rate (e.g., ⅘, or ⅔) ifconditions are relatively good and less gain is required, thereby savingbandwidth overhead. Alternatively, if the conditions are less stable(for example, if the receiver is moving in a vehicle at high speeds),and additional gain is desirable, a higher coding rate such as ⅓ or ¼may be desirable, at the cost of increased bandwidth overhead.

FIG. 10—Block Processor

FIG. 10 is a diagram illustrating the block processing involved inproducing M/H data blocks, the primary function of which is to providean outer-encoding concatenated with the standard 8-VSB trellis encoding.

FIG. 11—Payload Length

FIG. 11 is a table showing payload length as a function of SCCC BlockMode and Frame Mode (parameters in the TPC channel, which is describedbelow) for each region of an M/H Frame.

FIG. 12—SCCC Output/Input Block Length (SOBL/SIBL)

FIG. 12 is a table showing the SCCC Output Block Length forcorresponding SCCC Input Block Lengths at various rates. Each of theadditional rates (e.g., R=⅓, R=⅔, R=⅘) can be accommodated provided theSCCC Input Block Length (SIBL) is adjusted to maintain the original SCCCOutput Block Length (SOBL) for a given M/H Block.

FIGS. 13A and 13B—Cross Stream Association, Augmented Main StreamEncoding

FIGS. 13A and 13B illustrate ways to stream audiovisual informationaccording to various embodiments. In FIG. 13A, ‘main stream data’, i.e.,data intended for stationary devices, is sent in one stream. The mainstream may or may not include its own error correction informationaccording to various embodiments. In addition to the main stream data,there may be a parade for mobile devices, i.e., an audiovisualinformation stream intended for devices which are configured to useadditional error correction coding. A parade, as used herein, refers toa sequence of transmitted M/H slots assigned to carry a particularservice. As one example, in the ATSC standard, to accommodate bothstationary and mobile devices, there may be a main stream forexisting/stationary services and an M/H stream for mobile and/orhandheld devices. In prior art approaches, such separate streams may berequired in order to transmit audiovisual information to both stationaryand mobile devices, because the existing/stationary devices may not beconfigured to recognize the M/H stream, while mobile devices may not beable to use the main stream because it does not have sufficient errorcorrection coding to enable reliable reception if the mobile device ismoving or otherwise in less than ideal reception conditions.

In FIG. 13B, there is still a main stream parade, and a M/H paradeincluding additional error correction information, however, the M/Hparade does not include separate audiovisual information. Since theadditional error correction is still sent in a separate parade than themain stream, stationary/existing devices may be able to use the mainstream audiovisual information even if they are not configured to usethe additional error correction information. There may also be controlinformation, usable by mobile devices, for linking or associating theadditional error correction information to corresponding information inthe main stream. In this way, mobile devices may also be able to use themain stream audiovisual information. Thus, by sending the audiovisualinformation in a separate stream than the error correction codinginformation, but associating them, both mobile and stationary devicesmay be able to use the same audiovisual information, potentiallyeliminating the redundancy of multiple audiovisual streams, as forexample shown in FIG. 13A. The extra bandwidth that this frees up isindicated by the blank space shown at the end of each parade in FIG.13B.

The association of information between multiple data streams is what isreferred to herein as cross stream association. In particular, whencross stream association is used to associate additional errorcorrection information with a main audiovisual information stream, theresulting data stream is what is referred to herein as an augmented mainstream.

FIG. 14—Augmented Main Stream Encoding with a Convolutional Encoder

FIG. 14 illustrates two possible coding structures resulting fromaugmenting the main stream. The transmitted bits represent the data bitstransmitted in the main stream. As shown, they may correspond to theinput (data) bits in a systematic convolutional encoder, e.g., theconvolutional coding scheme shown in FIG. 6. The same coding scheme maybe used to produce a pattern (e.g., complementary to the data stream) oferror correction coding bits. These “augmented” bits may be sent in aseparate stream than the main stream, e.g., as described with regard toFIG. 13B. The augmented bits may be associated with the appropriate databits (e.g., with control information), such that a mobile device mayable to retrieve the error correction coding bits and the data bits andthereby effectively receive ½, ¼, or otherwise coded coding structure. Astationary device which is unable to use the additional error correctioninformation may simply ignore (in some embodiments, it may be unable torecognize) the control information associating the augmented bits withthe main stream data bits. The stationary device may thus also be ableto use the main stream service; in other words, augmented streamencoding may enable data sharing between services, e.g., in oneembodiment, both legacy ATSC services and ATSC M/H services may be ableto share the same main stream data.

FIG. 15—Augmented Service Multiplex

FIG. 15 illustrates one possible embodiment of an augmented servicemultiplex. As shown, the augmented service data may be transported in aseparate parade, bypassing portions of M/H processing, such as a frameencoder, convolutional coder, null encapsulation, and signaling. Assuch, the main service data may remain accessible to a legacy receiverwhile also benefiting from additional training to permit reliable mobilereception.

FIGS. 16A and 16B—Augmented Stream Organization

A Fast Information Channel (FIC) may be used to enable transmission ofmanagement layer controls. The FIC may operate under a transport layer,in some embodiments providing channel content type but not contentconfiguration. The FIC can be used to notify a receiver where to locatestream content and how to use that content in maximizing systemperformance. In one embodiment, no zero padding or byte stuffing will beused to align the state of an augmentation block to a particular M/Hgroup. Instead, the start location must be signaled (i.e., because itwill vary). The augmentation may occur at regular intervals, allowing areceiver to compare what it calculates to be the next block to what issignaled by the FIC. This may allow the use of multiple FIC packets toimprove reliability. FIG. 16A shows an example of how the main serviceparade may be augmented, with FIC pointers between an augmented streamand associated main stream blocks.

FIG. 16B shows a similar example of pointers between augmented streamblocks and M/H blocks. In this case, instead of being used to augment amain service stream, the augmentation blocks may be used for augmentingan audiovisual information stream intended for mobile devices.Augmentation of an M/H service may require less information thanaugmentation of a main stream service, e.g., because there may be aTransmission Parameter Channel (TPC) (described in more detail below)which gives the size of the main service and the M/H service may alreadybe synchronized to the start of an M/H frame. However, in someembodiments the redundant information is still signaled, because thesignaling must already be allocated to the main stream augmentation.This may allow for future unforeseen expansions.

FIGS. 17A and 17B—Bit Stream Syntax for the FIC Extended Segment andAugmentation Type Mode

FIG. 17A shows one possible syntax for an FIC command associating anerror correction coding (augmentation) block with a block of audiovisualinformation. The portions of the command that specifically associate theaugmented parade with a service block are shown in bold. In theembodiment shown, these fields may include:

Associated Parade ID (7 bits)—The ID of the associated parade thisaugmentation is to be applied. The value of 127 is reserved to specifythe main service.

Station for service (7 bits)—the station number the service can be foundon. This allows for frequency diversity and also allowed for theaugmentation to exceed 19.28 Mbps since it can be placed on a differentstation.

Augmentation Type (4 bits)—FIG. 17B shows the syntax of this fieldaccording to this embodiment. Augmentation type describes the typeand/or pattern of the error correction coding.

Length n (4 bits)—specified the number of nibbles (4 bit blocks) in thefollowing field

Start of Next Augmentation Block (4n bits)—Value in parade payload bytesfrom the start of this group location to the start of the nextaugmentation block.

Block Size of the service (4n Bits)—Count in segments of the number ofsegments to apply the data to.

Size of Augmentation Block (4n Bits)—Number of bytes for theaugmentation.

Start of Payload data (4n Bits)—number of segments from the currentgroup to the start of the payload. This value can be negative so thefield is a signed integer. This value should always be 0 for theaugmentation of an M/H parade. This field will also specify whereredundant information can be found as an alternative to the current datastream (i.e. diversity). If a stream has no redundancy or augmentationthen this value will point to the current service and always be 0.

FIG. 18—Transport Parameter Channel Syntax

In addition to the FIC (which operates under the Transport Layer), theremay also be a Transmission Parameter Channel (TPC) for signaling withinthe PHY layer. The TPC data has the following properties:

-   Averaging probabilities of multiple data values gives better noise    immunity-   Frame location information via counters-   Frame FEC setup-   Fixed in size-   31 bits available to (reserved for) future PHY signaling-   The TPC can be used for some basic signaling, such as indicating the    presence of an augmented parade. In order to signal an augmented M/H    parade for either the main service or a robust M/H service, the TPC    may be extended to support such new modes by using some of the    reserved bits. FIG. 18 shows the TPC syntax according to one    embodiment of the present invention, where the fields used to signal    the augmented parade are shown in bold. In the embodiment shown,    these fields may include:

Parade Type (2 bits)—Specifies the type of parade that is being sent.The possible values and corresponding meanings of this field accordingto one embodiment are shown in Table 1.

TABLE 1 Parade Type Parade Type Description 00 M/H Encoded 01 M/HAugmented 10 Main Augmented 11 Reserved

Block Encoder Mode (2 bits)—Specifies the type of block encoder used.The block encoder mode can be used to disable the addition of RS+CRC, asshown in Table 2.

TABLE 2 Block Encoder Mode Block Encoder Mode Description 00 RS + CRCadded 01 None 10 Reserved 11 Reserved

SCCC Outer Code Mode Extensions (2 bits each)—May be used to signalrates (e.g., ⅓, ⅔, ⅘, etc.) beyond the basic ¼ and ½. An SCCC Outer CodeMode Field may signal an extension to an SCCC Outer Code Mode Extension,as shown in Table 3.

TABLE 3 SCCC Outer Code Mode SCCC outer code mode Description 00 Theouter code rate of a SCCC Block is ½ 01 The outer code rate of a SCCCBlock is ¼ 10 The outer code rate of a SCCC Block is none (nothingadded) 11 Extend to SCCC_outer_code_mode_extension

FIG. 19—Transmission Diversity

FIG. 19 shows various methods of transmission diversity. By sending dataseparated by a time delay and/or at a different frequency, servicereliability can be improved, for example in the presence of burst noiseor deep channel fading. Transmission diversity can include simplysending redundant (backup) streams at different delays or frequencies(as shown in and described with respect to FIGS. 20 and 21 below), ormay be coupled with the concepts of cross stream association to producenested stream encoding, wherein multiple complementary streams aretransmitted, separated in time and/or frequency, containing additionalerror correction coding information (non-systematic encoding, i.e., justthe error correction coding information without the audiovisualinformation). The multiple complementary streams may then be associatedwith the primary data stream (the audiovisual information) at thereceiver. Nested Stream Encoding is described in more detail with regardto FIG. 22.

A further extension of transmission diversity is what is referred toherein as stagger casting. In this case, multiple complementary streamsof error correction coding information may be transmitted, however,unlike nested stream encoding, each stream may retain sufficientinformation to permit decoding when received alone. In other words, eachstream may employ systematic encoding. In this case, although eachstream may be decoded when received alone, reception of multiple suchstreams (e.g., including complementary error correction codinginformation, similar to nested stream encoding) may effectively producea higher coding rate, permitting a lower receive threshold.

FIG. 20—Time Diversity

FIG. 20 shows a data stream with both time-diverse and non-time diversecontent. Content A includes primary content blocks A1 as well as backupcontent blocks A2, which are repeated (redundant) versions of the A1content blocks. Thus, if a burst destroys A1 content block 2, the backupA2 content block 2 may be used. In the example shown, Content B has nobackup content and is not time diverse. While FIG. 20 shows timediversity as it can be used for repeating identical blocks of content,the concept of time diversity can similarly be applied to partially orentirely complementary data blocks, which may be associated with eachother using cross stream association (e.g., control information linkingthe time diverse content) as described herein. Time diversity may beused with or without frequency diversity as desired.

FIG. 21—Frequency Diversity

FIG. 21 shows multiple data streams transmitted on differentfrequencies, i.e., station A transmits on a first frequency and stationB transmits on a second frequency. As shown, Content A and Content B arefrequency diverse; that is, both content A and content B are transmittedon both station A and station B. Content C, which is only transmitted onstation A, and content D, which is only transmitted on station B, arenot frequency diverse. While FIG. 21 shows frequency diversity as it canbe used for repeating identical blocks of content, the concept offrequency diversity can similarly be applied to partially or entirelycomplementary data blocks, which may be associated with each other usingcross stream association (e.g., control information linking the timediverse content) as described herein. Frequency diversity may be usedwith or without time diversity as desired.

FIG. 22—Nested Stream Encoding

FIG. 22 illustrates one possible embodiment of nested stream encoding.In the example shown, stream 2200 may be the main stream, encoded at arate of ⅔. Streams 2202, 2204, and 2206 may be non-systematicaugmentation streams; in other words, each of these streams may containonly error correction coding bits. Each stream may be transmitted at aseparate time and/or frequency. As can be seen, each augmentation stream2202, 2204, and 2206 is complementary to each other augmentation streamand to the main stream 2200. Thus, if all four streams are received andassociated with each other, they may effectively produce a stream 2008with a higher coding rate of ¼. Alternatively, it may be noted that evenif only the main stream 2200 and the stream 2206 are received, thisstill effectively increases the coding rate of the main stream from ⅔ to½. Thus, the advantages of time and/or frequency diversity may beachieved without incurring the additional overhead of repeating thecontent data.

FIG. 23—Equivalent M/H R=½ Canonical Forms

Stagger casting is a further extension of the nested stream encodingconcept, whereby complementary streams are encoded in a way that permitslayered encoding coupled with potential for reliable data recovery basedon receipt of either stream alone. The streams may be staggered in timeand/or frequency to combat temporary signal dropout, as previouslydiscussed. The complementary streams may be encoded with minimal overlapto conserve bandwidth, however, each stream still retains sufficientinformation (in terms of data (AV information) and code bits (errorcorrection coding information) to enable stand alone data recovery. Whenboth streams are received and associated with one another, theinformation builds together to permit reception at lower receivethresholds. To do this in the M/H system, slight modifications to theconvolutional encoder (e.g., as shown in FIG. 6) may be necessary.

Currently the M/H system offers (C0,C2),(C1,C4) and (C0,C1),(C3,C4)modes for ¼ rate encoding. For ½ rate coding the M/H system offers(C0,C1). It is possible to split the ¼ rate code (C0,C2),(C1,C4) intotwo separate streams. The two streams would be (C0,C2) and (C1,C4). FIG.23 shows what the equivalent canonical forms look like for betterunderstanding of the encoder.

It can be seen that (C0,C2) is just a delayed parity version of the(C0,C1) code. Decoding this mode would only require a simple adjustmentto a trellis decoder's state machine.

The (C1,C4) code has two problems. Firstly, it is a non-systematic code.However, the M/H convolutional encoder has a benefit that the memory isreset to 0 at the start of every SCCC block system, putting the trellisinto a known state. The C4 code is a feedforward methodology. Due tocancelation of terms, C4 is the sum of C0 with a delayed version ofitself. As the starting state is known, C4 can be transformed to C0,which means that a systematic decoder for the (C1,C4) code can beconstructed.

The second issue with the (C1,C4) code is that equivalent code bit C4 isplaced into the Z1 bit of the output symbol while the C1 bit is placedin the stronger Z2 bit. This opens up the issue of using only the C4 bitto decode the signal, since this bit by itself will be weaker thanhaving it in the Z2 bit. However, may not matter if it is assumed thatthe decoding is for R=½ in this mode; in this case the decoder will justbe more strongly biased by the parity code.

FIG. 24—SCCC Block Mode Extension

In order to enable the additional R=½ modes described with respect toFIG. 23, these extended rate modes must be signaled. One part of thesignaling may include modification to the TPC signaling. For example,the value ‘11’ for the field ‘SCCC_Block_Mode’ shown in FIG. 18 may beused to mark a 2-bit ‘SCCC_Block_Mode_Extension’ field. This new fieldmay be defined as shown in FIG. 24. For example, as shown, in the newfield there may be provision for the R=½ convolutional coding modesderived from the R=¼ (C0,C2),(C1,C4) mode as described with respect toFIG. 23.

FIG. 25—Convolutional Encoder Output Symbols (Bit Pairs)

In order for the TPC signaling modification described with respect toFIG. 24 to be effective, the convolutional encoder must define itsoutput in a way consistent with this signaling. FIG. 25 shows oneexample of how the convolutional encoder of FIG. 6, as modified toderive the additional R=½ modes as described with respect to FIG. 23,may define its output in a way consistent with the signaling defined inFIG. 24.

FIG. 26—Stagger Casting

As described with respect to FIG. 23, it is possible to split the R=¼code (C0,C2),(C1,C4) into two separate streams. Together with the R=½code (C0, C1), these make up three partially complementary, partiallyoverlapping, systematic (or effectively systematic in the case of (C1,C4)) R=½ coding patterns. These coding patterns are shown in FIG. 26.Since each coding pattern is systematic (or effectively systematic), theencoded audiovisual information may be retrieved by a mobile device fromany of the three coding patterns, even if the other coding patterns aredropped or otherwise not received correctly. For example, if eachpattern is transmitted in a separate stream (e.g., separated from theother coding patterns in time and/or frequency), even if one or more ofthe coding patterns are destroyed because of burst noise, a deep fade,and/or any other reason, at least one coding pattern may still bereceived. Even a single received systematic coding pattern may besufficient for a mobile device to retrieve and present the encodedaudiovisual data, if the signal to noise ratio for the received codingpattern is sufficient. On the other hand, if more than one staggercasted coding patterns are received by a mobile device, the coding ofeach coding pattern may build on the complementary coding of the othercoding patterns to effectively form a more robust stream (e.g., a highereffective error correction coding rate), potentially enabling retrievaland presentation of the audiovisual information at a lower signal tonoise ratio than would be possible if fewer of the coding patterns arereceived by the mobile device.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

We claim:
 1. A wireless device, comprising: an antenna; and receiverlogic, wherein the antenna and the receiver logic are configured to:receive control information indicating that a first stream and a secondstream are associated; receive the first stream, wherein the firststream comprises audiovisual information and forward error correction;receive the second stream, wherein the second stream comprisesaudiovisual information and forward error correction, wherein theaudiovisual information comprised in the first stream and theaudiovisual information comprised in the second stream are at leastpartially complementary; and associate the first stream and the secondstream based at least in part on the control information.
 2. Thewireless device of claim 1, wherein the wireless device furthercomprises a display and one or more speakers, wherein the wirelessdevice is further configured to: process the audiovisual informationcomprised in the first stream and the audiovisual information comprisedin the second stream together; and present the processed audiovisualinformation using the display and the one or more speakers.
 3. Thewireless device of claim 1, wherein the first stream is also configuredfor processing and presentation by a wireless device without the secondstream.
 4. The wireless device of claim 1, wherein the forward errorcorrection comprised in the first stream comprises different forwarderror correction relative to the forward error correction comprised inthe second stream.
 5. The wireless device of claim 1, wherein thewireless device is further configured to: receive control informationindicating that the first stream is transmitted at a different time thanthe second stream.
 6. The wireless device of claim 1, wherein thecontrol information is received separately from the first stream andfrom the second stream.
 7. A system, comprising: receiver logicconfigured to cause a wireless device to: receive control informationindicating that a first stream and a second stream are associated;receive the first stream, wherein the first stream comprises audiovisualinformation and forward error correction; receive the second stream,wherein the second stream comprises audiovisual information and forwarderror correction; and associate the first stream and the second streambased at least in part on the control information.
 8. The system ofclaim 7, wherein the receiver logic is further configured to cause thewireless device to: process the audiovisual information comprised in thefirst stream and the audiovisual information comprised in the secondstream together based at least in part on the control information. 9.The system of claim 7, wherein the first stream is also configured forprocessing and presentation by a wireless device without the secondstream.
 10. The system of claim 7, wherein the forward error correctioncomprised in the first stream comprises different forward errorcorrection relative to the forward error correction comprised in thesecond stream.
 11. The system of claim 7, wherein the receiver logic isfurther configured to cause the wireless device to: receive controlinformation indicating that the first stream is transmitted at adifferent time than the second stream.
 12. The system of claim 7,wherein the control information is received separately from the firststream and from the second stream.
 13. The system of claim 7, whereinthe audiovisual information comprised in the first stream and theaudiovisual information comprised in the second stream are at leastpartially complementary.
 14. A system, comprising: transmit logicconfigured to cause a transmission system to: generate a first stream,wherein the first stream comprises audiovisual information and forwarderror correction; generate a second stream, wherein the second streamcomprises audiovisual information and forward error correction; generatecontrol information indicating that the first stream and the secondstream are associated; transmit the first stream; transmit the secondstream; and transmit the control information.
 15. The system of claim14, wherein the transmit logic is further configured to cause thetransmission system to: receive an audiovisual content stream, whereinboth the first stream and the second stream are generated based at leastin part on the received audiovisual content stream.
 16. The system ofclaim 14, wherein the first stream is also configured for processing andpresentation by a wireless device without the second stream.
 17. Thesystem of claim 14, wherein the forward error correction comprised inthe first stream comprises different forward error correction relativeto the forward error correction comprised in the second stream.
 18. Thesystem of claim 14, wherein the transmit logic is further configured tocause the transmission system to: transmit the second stream at adifferent time than the first stream, wherein the control informationfurther indicates that the second stream is transmitted at a differenttime than the first stream.
 19. The system of claim 14, wherein thecontrol information is transmitted separately from the first stream andfrom the second stream.
 20. The system of claim 14, wherein theaudiovisual information comprised in the first stream and theaudiovisual information comprised in the second stream are at leastpartially complementary.